textproduct: Quad Cities

KEY MESSAGES

- A clipper-like system late Monday night into Tuesday morning is forecast to bring isolated (20-40%) showers and thunderstorms to the region.

- Warm up expected late week with temperatures reaching into the 80s by Friday as the next storm system approaches.

SHORT TERM /THROUGH TONIGHT/

Issued at 204 AM CDT Mon May 11 2026

Thin cloud cover has been found over our northeastern counties, as well as southwestern counties at times overnight, as a weak boundary remains over the CWA. As of 2 AM, temperatures are still holding in the mid 40s north to lower 50s central and south. So far, temperatures are not falling into the 30s but with several hours left before dawn, will let the frost headline ride. If temperatures do not reach the mid 30s, we could clear the headline out after sunrise.

Today is a rare quiet weather day this spring, with high pressure moving over our CWA. Mostly sunny should last through most of the day, though increasing cirrus and some AC is possible late this afternoon through tonight as warm advection aloft begins to increase. Highs today remain in the middle of a tightly clustered NBM window of guidance, in the mid 60s northeast to around 70 central, and mid 70s in the southwest.

Tonight, with the increase in mid/high clouds, as well as increasing south/southeast winds (10-15 mph) will help hold temperatures up into the 50s, except for our eastern counties, were low may fall as cold as the lower 40s with lighter winds in those areas.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 204 AM CDT Mon May 11 2026

Tuesday... A shortwave trough diving south from Ontario will generate a mid-level f-gen band over Wisconsin and northern Illinois, providing cloud cover and light rain to the our northern CWA. As the clipper-style low pressure swings into northern Wisconsin, a cold front is pushed southward into the area. Limited moisture return from the south (seen in dew points only in the 40s) should limit precipitation coverage to along the front. Storms that do develop are forecasted to move southeastward around 45 mph. Therefore, it will not take a lot of mixing to transport this momentum to the surface which is why the SPC has a Marginal (1 out of 5) Risk for severe storms on Tuesday with damaging winds as the primary threat. Regardless of storm development, southwesterly winds are forecasted to be gusting up to 45 mph ahead of the front and advect in warmer air as seen with highs in the upper 70s to mid-80s.

As the cold front clears the area by sunset, northwesterly flow sets in with gusts still up to 35 mph possible. As the skies clear out, the lows should drop back into the low 50s despite the huge warm up during the day.

Wednesday... Northwesterly flow aloft returns as the region will be sandwiched between a longwave trough to the east and ridging over the Rockies. Conditions will be mostly dry besides some light lingering showers in northern Illinois from a weak surface trough on the backside of the low pressure over Upstate New York. Northerly flow is forecasted to cool down highs Wednesday back into the mid- 60s to mid-70s across the area, similar to conditions on Monday. Lows on Wednesday night are forecasted to drop back into the 40s as the winds go nearly calm. There is the potential for radiational fog to develop, but the probabilities are still low.

Thursday-Friday... A shortwave trough over the northern Rockies ejects into the Northern Plains, shifting the ridge axis over the Upper Mississippi River Valley on Thursday. This will deepen a developing mid-latitude cyclone over Saskatchewan as a cold front propagates east of the Rockies. Once again, the low-level flow returns to southerly ahead of this next low pressure system, advecting in warmer and moist air, but unlike Tuesday, the prolonged period of return flow will allow PWATs to gradually climb Thursday into Friday morning above 1 inch. A pre-frontal trough will support isolated showers and thunderstorms overnight on Thursday into Friday morning, but model uncertainty grows as we get into Friday on the exact timing of the cold front. The ECMWF ensembles have the low pressure over Saskatchewan booking it eastward across Canada with the mid-level trough, pushing the front through on Friday night, but the GFS ensembles has a bimodal distribution in solutions with a group agreeing with the ECMWF and another with a slower low pressure system over the Northern Plains. This will have a great influence on the timing and coverage of storms that develop on Friday as seen by the spread in LREF 6-hourly precipitation of 0.25 inch across the CWA.

Regardless, there will be a warming trend starting Thursday into Friday with highs in the 80s becoming more likely (40-60%) across the entire CWA.

Saturday-Sunday... While Saturday's weather will be dependent on if the cold front Friday night clears the area, there is greater agreement among ensemble models that another low pressure system will develop across the Great Plains on Sunday, bringing PoPs back up across the region. PWATS will likely stay above 1 inch through the weekend as seen in the LREF probability of exceedance being 60- 80%, keeping the threat at heavy rainfall elevated.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 605 AM CDT Mon May 11 2026

High pressure over the area will bring generally light north to northeast winds today along with clear skies. Tonight, as this high pressure area moves east, southeast winds will increase through the night, along with high cloud cover, well above 15kft. Some gusts are possible overnight through sunrise Tuesday, as this southeast wind field increases.

Beyond the end of the period, an approaching cold front from the northwest will bring a chance for high based cig rain showers to the area Tuesday, along with gusty southwest winds potentially over 35kts.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Frost Advisory until 8 AM CDT this morning for IAZ040>042. IL...Frost Advisory until 8 AM CDT this morning for ILZ001-002. MO...None.